1. Field of the Invention
The present invention relates to a method for removal of undesirable foreign matter from the interior of existing duct systems. More specifically, the method comprises the insertion of a plurality of members with a static electrical charge thereon into a stream of air passing through a duct to remove the foreign matter without damage to the duct system.
2. Description of the Prior Art
The primary method for cleaning heating, ventilating and air conditioning ("HVAC") duct systems located within structures has been to insert vacuum cleaner wands and hoses through access ports into the ducts for the direct removal of undesirable foreign matter that has collected within the duct or has adhered to the duct surfaces. To be effective this method requires that numerous access ports be made in the ducts as the vacuum cleaner pipes and hoses extend for short distances and are unable to reach around corners in the duct. As ducts normally are located above the ceiling of the structure, numerous unsightly access panels are required in the ceiling to gain access to the access ports in the ducts. This method of cleaning is slow and laborious requiring access to many access ports. Furnishings must be moved in order to open the access ports and control of the loose foreign matter is difficult.
An improved method for cleaning ducts is disclosed by U.S. Pat. No. 3,485,671 issued to Stephen. This method utilizes a cleaning material of walnut shells ground to a consistency of course sand or felt, foam, plastic and other materials of various shape and sizes that are inserted within the duct system and moved by a stream of air that is passed through the duct system from the insertion point to an outlet point where the cleaning material and foreign matter is collected. However, the fine cleaning material and the fine dust particles are difficult to trap and often escape into the interior of the structure. Also, the smaller particles require a large device to capture and separate the cleaning material from the foreign matter. Cleaning materials that are small or finely ground may be carried by the stream of air into the filter system, prematurely clogging the filters.
Therefore, there is a need to capture the finer dust so that it may be removed from the air in the duct and kept from escaping into the facility. There is also a need for a simple portable system using a cleaning material that is easily separable from the air stream.